Hydraulic fracturing system and method

ABSTRACT

A hydraulic fracturing system and method are disclosed. The system includes a pulse-inducing system configured to deliver pulses of fluid to a fluid stream upstream of the wellbore. The pulse-inducing system can include at least one supplemental pump, at least one pulsation valve, and at least one pressure storage vessel. A hydraulic fracturing method can comprise generating a fluid stream via a primary pumping system, generating a pulsed output via a pulse-inducing system, and directing the pulsed output into the fluid stream upstream of a wellbore.

RELATED APPLICATIONS

This non-provisional patent application is a continuation applicationunder 35 U.S.C. §120 of U.S. patent application Ser. No. 14/537,621,entitled HYDRAULIC FRACTURING SYSTEM AND METHOD, filed on Nov. 10, 2014,which is a continuation-in-part application under 35 U.S.C. §120 of U.S.patent application Ser. No. 14/515,896, entitled HYDRAULIC FRACTURINGSYSTEM AND METHOD, filed Oct. 16, 2014, the entire disclosures of whichare hereby incorporated by reference herein.

FIELD

The present disclosure relates to hydraulic fracturing systems andmethods for assembling and using the same.

BACKGROUND

Hydraulic fracturing can be used to stimulate and/or increase productionfrom oil and gas wells. In a hydraulic fracturing process, fracturingfluid is pumped into a wellbore. Inside the wellbore, hydraulic pressureis employed to force the fracturing fluid into a formation. When thefracturing fluid enters the formation, the formation can fracture andchannels and/or fissures can be created within the formation. Fracturingfluid can be pumped into the fractured formation to expand the fissuresand/or to increase the size and/or quantity of fissures in theformation. The fracturing fluid can include water, chemicals, andproppants, such as sand, metal, and/or glass beads, for example, whichcan hold the fissures open. Because hydraulic fracturing can createfissures within a formation and can hold the fissures open, hydraulicfracturing can stimulate the release of oil and gas from the formation.

The equipment, including the pump(s), conduit(s), and/or manifold(s),for example, utilized in a hydraulic fracturing operation can operate upto and/or be rated to operate below a pressure threshold or maximumpressure P_(max). In certain instances, the maximum pressure P_(max) canbe limiting factor in a hydraulic fracturing operation. For example,when a hydraulic fracturing system is operated at its maximum pressure(P_(max)), significant volumes of oil and/or gas may remain in the well.In such instances, it can be desirable to improve the effectiveness of ahydraulic fracturing operation, such that additional volumes of gasand/or oil can be extracted from the well, while operating below themaximum pressure (P_(max)) of the equipment.

Additionally, it can be desirable to extract gas and/or oil from thewell using less water and/or less fracturing fluids, with reducedhorsepower requirements and/or reduced emissions, and/or in fewer stagesand/or more quickly. Additionally, it can be desirable to utilizehydraulic fracturing processes in expanded and/or additional areas. Itcan also be desirable to reduce the costs of hydraulic fracturingoperations, reduce the static pressure required to fracture theformations and/or force the fracturing fluid into the formations, and/orimprove the safety conditions at a hydraulic fracturing site. Moreover,it can be desirable to provide real time feedback information to theoperators of the hydraulic fracturing equipment.

The foregoing discussion is intended only to illustrate various aspectsof the related art in the field at the time and should not be taken as adisavowal of claim scope.

SUMMARY

In at least one form, a hydraulic fracturing system for introducingfracturing fluid into a wellbore comprises a manifold comprising a fluidoutlet and a plurality of fluid inlets. The hydraulic fracturing systemfurther includes a plurality of primary pumps, each of the primary pumpsis fluidically coupled to one of the fluid inlets, and the primary pumpsare configured to deliver a fluid stream to the fluid outlet. Thehydraulic fracturing system further includes a pulse-inducing systemconfigured to deliver pulses of fluid to the fluid stream upstream ofthe wellbore, and the pulse-inducing system comprises a supplementalpump, a pulsation valve, and a pressure storage vessel intermediate thesupplemental pump and the pulsation valve.

In at least one form, the supplemental pump comprises a firstsupplemental pump, the pulsation valve comprises a first pulsationvalve, the pressure storage vessel comprises a first pressure storagevessel, and the pulse-inducing system further comprises a secondsupplemental pump, a second pulsation valve, and a second pressurestorage vessel intermediate the second supplemental pump and the secondpulsation valve.

In at least one form, the manifold comprises a primary manifold, and thepulse-inducing system further comprises a first system manifoldcomprising a first inlet fluidically coupled to the first supplementalpump and a second inlet fluidically coupled to the second supplementalpump a second system manifold comprising a first outlet fluidicallycoupled to the first pulsation valve and a second outlet fluidicallycoupled to the second pulsation valve.

In at least one form, the first system manifold comprises a firstisolation valve intermediate the first inlet and the second inlet, andthe second system manifold comprises a second isolation valveintermediate the first outlet and the second outlet.

In at least one form, the hydraulic fracturing system further comprisesa control system in communication with the first pulsation valve and thesecond pulsation valve.

In at least one form, the control system is in communication with thefirst isolation valve and the second isolation valve.

In at least one form, the hydraulic fracturing system further comprisesa plurality of power units coupled to at least one of the primary pumps,first supplemental pump, or second supplemental pump, and the controlsystem is in communication with the plurality of power units.

In at least one form, the first pulsation valve is configured to deliverpulses of a first magnitude at a first frequency, and the secondpulsation valve is configured to deliver pulses of a second magnitude ata second frequency.

In at least one form, the first magnitude is different than the secondmagnitude.

In at least one form, the first frequency is different than the secondfrequency.

In at least one form, the manifold further comprises a supplementalinlet, and the pulse-inducing system is fluidically coupled to thesupplemental inlet.

In at least one form, the hydraulic fracturing system further comprisesa conduit extending from the fluid outlet to a wellhead of the wellboreand an auxiliary manifold intermediate the fluid outlet and thewellhead. The auxiliary manifold comprises a fluid inlet fluidicallycoupled to the pulse-inducing system.

In at least one form, the hydraulic fracturing system further comprisesa first conduit extending from the fluid outlet to a wellhead of thewellbore and a second conduit extending from the pulsation valve to thewellhead.

In at least one form, a hydraulic fracturing system, comprises amanifold comprising a first fluid outlet, a second fluid outlet, and aplurality of fluid inlets. The hydraulic fracturing system furthercomprises a plurality of primary pumps. Each of the primary pumps isfluidically coupled to one of the fluid inlets. The primary pumps areconfigured to deliver a first fluid stream to the first fluid outlet,and the primary pumps are configured to deliver a second fluid stream tothe second fluid outlet. The hydraulic fracturing system furthercomprises a pulse-inducing system fluidically coupled to the secondfluid outlet and configured to deliver pulses of fluid to the firstfluid stream.

In at least one form, the pulse-inducing system comprises a supplementalpump, a pulsation valve, and a pressure storage vessel intermediate thesupplemental pump and the pulsation valve.

In at least one form, the pulse-inducing system further comprises afirst system manifold and a second system manifold, and the pressurestorage vessel is intermediate the first system manifold and the secondsystem manifold.

In at least one form, the first system manifold comprises a first inletfluidically coupled to the supplemental pump, and the second systemmanifold comprises a first outlet fluidically coupled to the pulsationvalve.

In at least one form, the supplemental pump comprises a firstsupplemental pump, the pulsation valve comprises a first pulsationvalve, the pressure storage vessel comprises a first pressure storagevessel, and the pulse-inducing system further comprises a secondsupplemental pump, a second pulsation valve, and a second pressurestorage vessel intermediate the second supplemental pump and the secondpulsation valve.

In at least one form, the first system manifold comprises a second inletfluidically coupled to the second supplemental pump, and the secondsystem manifold comprises a second outlet fluidically coupled to thepulsation valve.

In at least one form, the first system manifold comprises a firstisolation valve intermediate the first inlet and the second inlet, andthe second system manifold comprises a second isolation valveintermediate the first outlet and the second outlet.

In at least one form, the hydraulic fracturing system further comprisesa control system in communication with the first pulsation valve and thesecond pulsation valve.

In at least one form, the first pulsation valve is configured to deliverpulses of a first magnitude for a first duration at a first frequency,and the second pulsation valve is configured to deliver pulses of asecond magnitude for a second duration at a second frequency.

In at least one form, the first magnitude is different than the secondmagnitude, and the first frequency is different than the secondfrequency.

In at least one form, a hydraulic fracturing method for introducingfracturing fluid into a wellbore comprises generating a fluid stream viaa primary pumping system, generating a pulsed output via apulse-inducing system, and directing the pulsed output into the fluidstream upstream of the wellbore.

In at least one form, generating the pulsed output in the hydraulicfracturing method comprises at least one of controlling a power unit, anisolation valve, or a pulsation valve of the pulse-inducing system.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features and advantages and the manner of attaining them willbecome more apparent and will be better understood by reference to thefollowing description of embodiments in conjunction with theaccompanying drawings, in which:

FIG. 1 is a schematic depicting a hydraulic fracturing system thatincludes a plurality of primary pumps, a manifold operably in fluidcommunication with the primary pumps, and a wellhead operably in fluidcommunication with the manifold, according to various embodiments of thepresent disclosure.

FIG. 2 is another schematic depicting a hydraulic fracturing system thatincludes the primary pumps and the wellhead of FIG. 1, and furtherincludes a supplemental pump and a manifold, further depicting themanifold operably in fluid communication with the supplemental pump andwith the primary pumps, according to various embodiments of the presentdisclosure.

FIG. 3 is another schematic depicting a hydraulic fracturing system thatincludes the primary pumps and the wellhead of FIG. 1, and furtherincludes the supplemental pump and the manifold of FIG. 2, according tovarious embodiments of the present disclosure.

FIG. 4 is another schematic depicting a hydraulic fracturing system thatincludes the primary pumps and the wellhead of FIG. 1, further includesthe supplemental pump of FIG. 2, and further includes a manifold influid communication with the supplemental pump and with the primarypumps, according to various embodiments of the present disclosure.

FIG. 5 is another schematic depicting a hydraulic fracturing system thatincludes the primary pumps and the wellhead of FIG. 1, and furtherincludes the manifold of FIG. 4 and a pair of supplemental pumps, andfurther depicts the manifold operably in fluid communication with thepair of supplemental pump and with the primary pumps, according tovarious embodiments of the present disclosure.

FIG. 6 is a chart depicting the output from a plurality of primarypumps, a pulsed pump, and the aggregated output of the primary andpulsed pumps, according to various embodiments of the presentdisclosure.

FIG. 7 is a chart depicting the output from a plurality of primarypumps, a pair of pulsed pumps, and the aggregated output of the primaryand pulsed pumps, according to various embodiments of the presentdisclosure.

FIG. 8 is a chart depicting the output from a plurality of primarypumps, a pair of pulsed pumps, and the aggregated output of the primaryand pulsed pumps, according to various embodiments of the presentdisclosure.

FIG. 9 is a chart depicting the output from a plurality of primarypumps, a pair of pulsed pumps, and the aggregated output of the primaryand pulsed pumps, according to various embodiments of the presentdisclosure.

FIG. 10 is a flowchart depicting a hydraulic fracturing method,according to various embodiments of the present disclosure.

FIG. 11 is another schematic depicting a hydraulic fracturing systemthat includes the primary pumps and the wellhead of FIG. 1 and themanifold of FIG. 2, and further includes a pulse-inducing system and anauxiliary manifold, according to various embodiments of the presentdisclosure.

FIG. 12 is another schematic depicting a hydraulic fracturing systemthat includes the primary pumps and the wellhead of FIG. 1 and themanifold of FIG. 2, and further includes the pulse-inducing system ofFIG. 12, according to various embodiments of the present disclosure.

FIG. 13 is another schematic depicting a hydraulic fracturing systemthat includes the primary pumps and the wellhead of FIG. 1 and thepulse-inducing system of FIG. 12, and further includes a manifold havingsupplemental inlets, according to various embodiments of the presentdisclosure.

FIG. 14 is a schematic depicting the pulse-inducing system of FIG. 12,according to various embodiments of the present disclosure.

FIG. 14A is a schematic depicting a control system for thepulse-inducing system of FIG. 12, according to various embodiments ofthe present disclosure.

FIG. 15 is a schematic depicting a pulse-inducing system, according tovarious embodiments of the present disclosure.

FIG. 16 is a flowchart depicting a hydraulic fracturing method,according to various embodiments of the present disclosure.

FIG. 17 is a flowchart depicting various steps for controlling apulse-inducing system, according to various embodiments of the presentdisclosure.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices, systems, and methods disclosedherein. One or more examples of these embodiments are illustrated in theaccompanying drawings. Those of ordinary skill in the art willunderstand that the devices and methods specifically described hereinand illustrated in the accompanying drawings are non-limiting exemplaryembodiments and that the scope of the various embodiments is definedsolely by the claims. The features illustrated or described inconnection with one exemplary embodiment may be combined with thefeatures of other embodiments. Such modifications and variations areintended to be included within the scope of the present disclosure.

Reference throughout the specification to “various embodiments,” “someembodiments,” “one embodiment,” or “an embodiment”, or the like, meansthat a particular feature, structure, or characteristic described inconnection with the embodiment is included in at least one embodiment.Thus, appearances of the phrases “in various embodiments,” “in someembodiments,” “in one embodiment”, or “in an embodiment”, or the like,in places throughout the specification are not necessarily all referringto the same embodiment. Additionally, reference throughout thespecification to “various instances,” “some instances,” “one instance,”or “an instance”, or the like, means that a particular feature,structure, or characteristic described in connection with the instanceis included in at least one instance. Thus, appearances of the phrasesin “various instances,” “in some instances,” “in one instance”, “in aninstance”, or the like, in places throughout the specification are notnecessarily all referring to the same instance.

Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more embodiment orinstance. Thus, the particular features, structures, or characteristicsillustrated or described in connection with one embodiment or instancemay be combined, in whole or in part, with the features structures, orcharacteristics of one or more other embodiment or instance withoutlimitation. Such modifications and variations are intended to beincluded within the scope of the present disclosure.

FIG. 1 is a schematic depicting a hydraulic fracturing system 100. Thedepicted hydraulic fracturing system 100 includes multiple primary pumps110 in fluid communication with a manifold 118. The depicted manifold118 is operably configured to be in fluid communication with a wellhead116. In the depicted arrangement, the primary pumps 110 are configuredto pump fluid and supply the pumped fluid to the wellhead 116 via themanifold 118, as well as various additional conduits and/or fluid lines,which are described in greater detail herein.

The primary pumps 110 can be high-pressure, high-volume fracturingpumps. In certain instances, the primary pumps 110 can be piston pumps.For example, the pumps 110 can be triplex or quintuplex piston pumps.The primary pumps 110 can be rated up to 22,000 psi and 115 gallons perminute, for example. At a lower value psi, the primary pumps 100 can berated up to 1375 gallons per minute, for example.

In various instances, the primary pumps 110 can be portable or mobile,for example. For example, each primary pump 110 can be mounted to avehicle 112, such as a truck or a trailer, for example. In certaininstances, the primary pumps 110 can be moved around the hydraulicfracturing site and/or can be relocated to different hydraulicfracturing sites. In some instances, multiple primary pumps 110 can bemounted to each vehicle 112. Referring to FIG. 1, the hydraulicfracturing system 100 can include six (6) primary pumps 110. In otherinstances, the hydraulic fracturing system 100 can include less than six(6) primary pumps 110 or more than six (6) primary pumps 110. Forexample, the hydraulic fracturing system 100 can include a singleprimary pump 110, or seven (7) or more primary pumps 110.

Referring still to FIG. 1, the primary pumps 110 can be powered bymotors 114. The motors 114 can also be mounted to the vehicles 112, forexample. In other instances, the motors 114 can be independent of thevehicles 112. In various instances, the motors 114 can be diesel-poweredmotors, for example. An exemplary, non-limiting motor is the Caterpillar3516C High Displacement marine engine, for example.

The primary pumps 110 can be fluidically connected to the wellhead 116via fluid lines 120, the manifold 118, and/or a conduit 122. Forexample, the vehicles 112 can be positioned near enough to the manifold118 such that a fluid line 120 connects each primary pump 110 to themanifold 118. The manifold 118 can include a plurality of inlets 130 andan outlet 132. In certain instances, the inlets 130 can beequally-spaced along the length of the manifold 118. In other instances,at least two inlets 130 can be unequally spaced. Additionally oralternatively, an inlet 130 can be positioned at an end of the manifold118. Referring to the embodiment depicted in FIG. 1, the manifold 118includes six (6) inlets 130, and each inlet 130 is coupled to a fluidline 120. In other instances, the manifold 118 can include additionalinlets 130, which may be used in certain operations and may remainunused in other operations. In various instances, the outlet 132 can bepositioned at an end of the manifold 118. In other instances, the outlet132 can be positioned along the length thereof and/or can be between twoinlets 130. Referring to the embodiment depicted in FIG. 1, the manifold118 includes a single outlet 132.

Fracturing fluid can flow along a fluid path or stream within themanifold 118. Referring to FIG. 1, a fluid path is indicated by thearrows. For example, fracturing fluid can enter the manifold 118 at theinlets 130 along the length of the manifold 118, and can flow toward theoutlet 132. Additionally, the manifold 118 can be connected to thewellhead 116 by a fluid line or conduit 122. The conduit 122 can beconfigured to deliver the fracturing fluid from the manifold 118 to thewellhead 116. The manifold 118 and conduit 122 can be rated to withstandhigh pressures.

Various components of fracturing fluid can be supplied to the primarypumps 110. For example, water, chemicals, and/or proppants can besupplied to one or more of the primary pumps 110. In certain instances,the hydraulic fracturing fluid supplied to the primary pumps 110 can bepre-mixed. For example, a slurry blender can mix various components, andthe mixture can be fed into one or more of the primary pumps 110. Insome instances, at least one primary pump 110 in the system 100 can becoupled to a water supply, at least one primary pump 110 in the system100 can be coupled to a chemical supply, and/or at least one pump 110 inthe system can be coupled to a proppant supply. For example, referringto FIG. 1, five (5) of the primary pumps 110 can supply water andchemicals to the manifold 118, and one (1) of the primary pumps 110 cansupply proppants to the manifold 118.

Proppants can include sand, metal and/or glass beads, and/or other solidmaterial, for example. The proppants can be various sizes, and multipledifferent size proppants can be included in a hydraulic fracturingfluid. Chemical additives can include lubricants, for example. Invarious instances, chemical additives and/or proppants can compriseapproximately 0.5% of the total volume of fracturing fluid delivered tothe wellhead 116.

The hydraulic fracturing system 100 may also include blenders or mixers,which can be configured to mix and blend the components of the hydraulicfracturing fluid, and to supply the hydraulic fracturing fluid to theprimary pumps 110. Water, chemicals, and/or proppants can be supplied tothe system 100 by additional vehicles, conduits, and/or conveyors. Thehydraulic fracturing system 100 can further include at least onemonitoring unit, which can monitor the composition and properties of thefracturing fluid, the volume of various supplies, and/or the flow rate,density, and/or pressure of the fracturing fluid at various locationswithin the system 100.

Referring still to FIG. 1, the primary pumps 110, which supplyfracturing fluid components and/or the fracturing fluid to the manifold118, can be configured and/or designed to supply a constant flow rateand uniform pressure into the wellbore 116. For example, an operator cancontrol the primary pumps 110 to supply a relatively constant flow rateand pressure. As a result, the flow rate and pressure of the fracturingfluid exiting the manifold 118 can be constant or substantiallyconstant.

In certain instances, the generation and introduction of pulses or wavesof fracturing fluid into the fluid stream can improve the effectivenessof the hydraulic fracturing operation. For example, pulses of fracturingfluid can create additional fissures within a formation and/or canenlarge preexisting fractures. More specifically, pulses of fracturingfluid can force a proppant, such as sand, for example, further down theborehole and into the formation to further enlarge the width and/orextend the length of the fissure and to hold the fissure open. Becausepulses of fracturing fluid can expand the fractured region, the additionof pulses to a fracturing operation can generate more oil and/or gasfrom the well. The addition of pulses can also extend hydraulicfracturing to areas where it would otherwise be cost prohibitive.

A pulse of fracturing fluid can also provide a pressure shock signal tothe operator. For example, microseismic energy measurement device(s) atthe surface can measure the microseismic events and/or conditions withinand around the wellbore. The device can then communicate themeasurements to the operator in real time.

The pulses of fracturing fluid within the fluid stream can bemechanically induced. For example, a supplemental pump can generate amechanical pulse or wave of fracturing fluid, which can be fed into thefluid stream. In certain instances, the supplemental pump can provideperiodic pulses, for example, which can generate corresponding periodicpressure increases or spikes within the fluid stream. In otherinstances, the pulses can be intermittent and/or sporadic. An operatorcan control the supplemental pump to deliver pulses periodically and/orsporadically, for example.

In certain instances, multiple supplemental pumps can be configured togenerate pulses of fracturing fluid, which can be delivered to the fluidstream. The pulses can be output from different supplemental pumps andcan have different frequencies and/or different amplitudes, for example.In various instances, the pulses from different supplemental pumps canoverlap, and/or can concurrently join the fluid stream. In otherinstances, the pulses can be staggered and/or can intermittently jointhe fluid stream. In certain instances, at least one supplemental pumpcan be configured to deliver small pulses to the fluid stream, and atleast one supplemental pump can be configured to deliver larger pulsesto the fluid stream.

Large pulses of fracturing fluid can break apart rock formations, thusproviding more channels and/or fissures within the formation.Additionally, large pulses of fracturing fluid can stimulate proppantsand lubricants in the fracturing fluid, and can force additionalproppants and lubricants within the fissures. Large pulses of fracturingfluid can also increase abrasion within the fissures, which can furtherenlarge a fissure. Moreover, large pulses of fracturing fluid canprovide a shock signal to the operator.

Small pulses of fracturing fluid can also stimulate proppants in thefracturing fluid, which can force additional proppants within thefissures. As proppants are forced further into the fissures, thefissures can be enlarged. Additionally, the small pulses of fracturingfluid can also provide a shock signal to the operator.

Referring now to FIG. 2, a hydraulic fracturing system 200 is depicted.Similar to the system 100, the hydraulic fracturing system 200 includesthe primary pumps 110, the motors 114, the vehicles 112, the fluid lines120 extending from the primary pumps 110, and the wellhead 116. Thehydraulic fracturing system 200 also includes a manifold 218 and asupplemental pump 240, which can be coupled to and/or driven by a powerunit and/or motor 244.

Referring still to FIG. 2, the manifold 218 includes a plurality ofinlets 230, which are coupled to the fluid lines 120. Accordingly, thefluid lines 120 permit fluid communication between the pumps 110 and themanifold 218. The manifold 218 depicted in FIG. 2 also includes aprimary outlet 232, which is coupled to a primary conduit 222. Theprimary conduit 222 extends between the manifold 218 and the wellhead116, and can operably permit a fluid stream to flow from the manifold218 to the wellhead 116. Similar to the hydraulic fracturing system 100,the primary pumps 110 can supply a constant flow rate and uniformpressure into the manifold 218. As a result, the flow rate and pressureof the fracturing fluid exiting the manifold 218 can be constant orsubstantially constant.

The supplemental pump 240 can be in fluid communication with themanifold 218 via a supplemental outlet 234 to the manifold 218 and asupplemental conduit 238. For example, a first portion of the fluidstream that is injected or pumped into the manifold 218 from the primarypumps 110 via the fluid lines 120 can flow from the inlets 230 towardthe primary outlet 232. Additionally, a second portion of the fluidstream that is injected or pumped into the manifold 218 from the primarypumps 110 can be diverted to the supplemental outlet 234. The secondportion of the fluid stream can flow to the supplemental pump 240, forexample.

In various instances, the supplemental pump 240 can be configured toinduce at least one pulse of fluid into the fluid stream. For example,the supplemental pump 240 can generate a pulse of fracturing fluid,which can flow from the pump 240 through a connecting conduit 242.Thereafter, the mechanically-induced pulse of fluid can join the fluidstream generated by the primary pumps 110.

The mechanically-induced pulse or pulses generated by the supplementalpump 240 can be generated outside of the wellbore, for example, and canbe transmitted to the fluid stream outside of the wellbore, for example.In various instances, the pulse or pulses can enter the fluid streamdownstream of the plurality of inlets 230 to the manifold 218. Forexample, the pulses can be introduced to the fluid stream between themanifold 218 and the wellhead 116. In various instances, thesupplemental pump 240 can transmit the mechanically-induced pulses tothe connecting conduit 242, and the connecting conduit 242 can becoupled to the primary conduit 222. For example, the connecting conduit242 and the primary conduit 222 can be coupled at a supplementalmanifold or union intermediate the manifold 218 and the wellhead 116.

In other instances, a supplemental, pulse-generating pump can transmitthe pulse or pulses to the fluid stream at the wellhead 116. Forexample, referring to FIG. 3, a hydraulic fracturing system 300 isdepicted. The hydraulic fracturing system 300 can be similar to thehydraulic fracturing system 200, except the connecting conduit 242 canextend between the supplemental pump 240 and the wellhead 116. In suchinstances, the mechanically-induced pulse(s) from the supplemental pump240 can be transmitted to the stream of fracturing fluid entering thewellhead 116.

In still other instances, a supplemental, pulse-generating pump cantransmit the pulse or pulses to the fluid stream within the manifold.For example, referring to FIG. 4, a hydraulic fracturing system 400 isdepicted. The hydraulic fracturing system 400 can be similar to thehydraulic fracturing system 200. Additionally, the hydraulic fracturingsystem 400 can include a manifold 418 having a plurality of inlets 430in fluid communication with the primary pumps 110 via the fluid lines120. The manifold 418 can also include a primary outlet 432 in fluidcommunication with the wellhead 116 and a supplemental outlet 434 influid communication with the supplemental pump 240, which can be coupledto and/or driven by a power unit and/or motor 244. The manifold 418depicted in FIG. 4 further includes a supplemental inlet 436 downstreamof the primary inlets 430. In the depicted arrangement, the connectingconduit 242 extends between the supplemental pump 240 and thesupplemental inlet 436 such that the pulse or pulses generated by thesupplemental pump 240 are directed into the fluid stream at the manifold418.

In various pump arrangements described herein, the supplemental pump 240(FIGS. 2-4) can receive fluid input from the manifold 218 (FIGS. 2 and3), 418 (FIG. 4). In other words, a portion of the fluid stream pumpedinto the manifold 218, 418 can be diverted to the supplemental pump 240.In such arrangements, the supplemental pump 240 can receive a portion ofthe fluid pumped into the system 200, 300, 400 from the primary pumps110. In various instances, the portion of the fluid stream directed tothe supplemental pump 240 can be diverted from the fluid stream beforeproppants and/or other additives are added to the fluid stream.Accordingly, clogging and/or contamination of the supplemental pump 240by proppants, for example, can be prevented and/or minimized.

In certain instances 5%-50% of the fluid from the primary pumps 110 canbe diverted to the supplemental pump 240. For example, approximately 25%of the fluid from the primary pumps 110 can be diverted to thesupplemental pump 240. In other words, as an example, if 80 barrel unitswere pumped into the manifold 218 (FIGS. 2 and 3), 418 (FIG. 4), 60barrel units could be directed to the primary outlet 432 as a fluidstream, and 20 barrel units could be directed to the supplemental outlet434. In other instances, less than 5% or more than 50% of the fluid fromthe primary pumps 110 can be diverted to the supplemental pump 240.

In various arrangements, the primary pumps 110 can generate a maximumpressure in the manifold 218 (FIGS. 2 and 3), 418 (FIG. 4). For example,when each primary pump 110 is operated to its maximum capacity, amaximum operating pressure P_(max) can be achieved in the manifold 218,418. Moreover, when a portion of the fluid stream is diverted to thesupplemental pump 240, as described herein, the pressure in the manifold218, 418 may drop. In certain instances, the pressure can drop 5%-50% inthe manifold 218, 418. For example, the pressure can drop approximately25% within the manifold 218, 418. In other instances, the pressure dropcan be less than 5% or more than 50%. When the supplemental pump 240redirects the diverted fluid stream back into the primary fluid streamas a pulse or wave of fluid, the pressure can increase toward themaximum pressure P_(max), for example. In certain instances, thepressure in the fluid stream can approach P_(max), however, the pressuremay not reach P_(max) due to frictional losses, for example. Forexample, the total pressure from the fluid stream in combination withthe peak of each pulse can approach P_(max) of the system.

In various instances, a hydraulic fracturing system can include one ormore supplemental pulse-inducing pumps. A hydraulic fracturing system500 is depicted in FIG. 5. The depicted hydraulic fracturing system 500includes the manifold 418, having a plurality of inlets 430 in fluidcommunication with the primary pumps 110 via the fluid lines 120. Themanifold 418 can also include the primary outlet 432 in fluidcommunication with the wellhead 116 and a supplemental outlet 434 influid communication with a pair of supplemental pumps 540 a, 540 b. Eachpump 540 a, 540 b can be coupled to and/or driven by a power unit and/ormotor 544 a, 544 b, respectively. The manifold 418 depicted in FIG. 5also includes the supplemental inlet 436 downstream of the primaryinlets 430. In the depicted arrangement, a pair of connecting conduits542 a, 542 b extend between the supplemental pumps 540 a, 540 b,respectively, and the supplemental inlet 436 such that the pulse orpulses generated by the supplemental pumps 540 a, 540 b are directedinto the fluid stream at the manifold 418.

In other instances, similar to the system 200, the connecting conduits542 a, 542 b and the primary conduit 222 can be coupled at asupplemental manifold or union intermediate the manifold 218 and thewellhead 116. In still other instances, similar to the system 300, theconnecting conduits 542 a, 542 b can transmit the pulses to the fluidstream at the wellhead 116. Additionally or alternatively, theconnecting conduits 542 a, 542 b can be in fluid connection with thefluid stream at different locations downstream of the inlets 230. Forexample, the first connecting conduit 542 a can be coupled to the fluidstream upstream of the second connecting conduit 542 b. Moreover, thesystem 500 can include additional supplemental pumps. For example, thesystem 500 can include three or more supplemental, pulse-generatingpumps.

Referring to FIG. 6, an output 610 from an exemplary set of primarypumps, such as the primary pumps 110 (FIGS. 1-5), for example, isdepicted. The output 610 comprises a substantially flat and/or constantoutput and is depicted in FIG. 6 as a horizontal line. A pulsed output640 from an exemplary supplemental pump, such as supplemental pump 240(FIGS. 2 and 3) and 440 (FIG. 4), for example, is also depicted in FIG.6. The pulsed output 640 comprises a plurality of equally spaced, equalamplitude pulses. The combination of the output 610 and the pulsedoutput 640 is also depicted in FIG. 6. For example, the combined andpulsed output 650 comprises the summation and/or aggregation of theoutput 610 and the pulsed output 640.

Referring to FIG. 7, the output 610 is depicted, as well as pulsedoutputs 640, 740 from an exemplary pair of supplemental pumps, such asthe supplemental pumps 540 a, 540 b (FIG. 5), for example. The firstpulsed output 640 comprises a plurality of equally spaced, equalamplitude pulses, and the second pulsed output 740 also comprises aplurality of equally spaced, equal amplitude pulses. The pulse amplitudeof the first pulsed output 640 can be greater than the pulse amplitudeof the second pulsed output 740, for example. For example, the pulseamplitude of the first pulsed output 640 can be 1.5 to 10 times greaterthan the pulse amplitude of the second pulsed output 740. In thedepicted instances, the pulse amplitude of the first pulsed output 640is 2.5 times greater than the pulse amplitude of the second pulsedoutput 740.

Additionally or alternatively, the pulse frequency of the second pulsedoutput 740 can be greater than the pulse frequency of the first pulsedoutput 640, for example. For example, the pulse frequency of the secondpulsed output 740 can be two (2) to ten (10) times greater than thepulse frequency of the first pulsed output 640. In the depictedinstances, the pulse frequency of the second pulsed output 740 is three(3) times greater than the pulse frequency of the first pulsed output640. In other instances, referring to FIG. 8, a second pulsed output 840comprises a pulse frequency ten (10) times greater than the pulsefrequency of the first pulsed output 640. The resultant total output 850is also depicted in FIG. 8.

Referring again to FIG. 7, in other instances, the pulsed output 640,740 that has the greater pulse amplitude and/or magnitude can also havethe greater pulse frequency. In certain instances, the pulse amplitudeof the first and second pulsed outputs 640, 740 can be equal orsubstantially equal. Additionally or alternatively, in some instances,the pulse frequency of the first and the second pulsed outputs 640, 740can be equal or substantially equal. For example, the pulse frequency ofthe first and second pulsed outputs 640, 740 can be equal orsubstantially equal and the pulse amplitudes of the first and secondpulsed outputs 640, 740 can be different. In other instances, the pulseamplitudes of the first and second pulsed outputs 640, 740 can be equalor substantially equal, and the pulse frequencies of the first andsecond pulsed outputs 640, 740 can be different.

Referring still to FIG. 7, the peaks and/or troughs of the first andsecond pulsed outputs 640, 740 can be offset. For example, each peak ofthe first pulsed output 640 can correspond to a trough of the secondpulsed output 740. Additionally, each trough of the first pulsed output640 can correspond to a peak of the second pulsed output 740.

In other instances, referring now to FIG. 9, various peaks and troughsof the pulsed outputs can be aligned. For example, a second pulsedoutput 940 can match the second pulsed output 740 of FIG. 7, however,the pulses can be offset by ½ a wavelength. As a result, the peaks ofthe first pulsed output 640 are aligned with the peaks of the secondpulsed output 940, for example, and the troughs of the first pulsedoutput 640 are aligned with the troughs of the second pulsed output 940,for example. The resultant combined output 950 is also depicted in FIG.9.

In an exemplary embodiment, referring again to FIG. 5, the firstsupplemental pump 540 can deliver 5 gallon pulses of fracturing fluidevery 0.25 seconds, which can result in pressure pulses of approximately8000 psi, for example. Additionally or alternatively, the secondsupplemental pump 540 can deliver 1 gallon pulses of fracturing fluidevery 0.125 seconds, which can result in pressure pulses ofapproximately 5000 psi, for example. The volume, time increment, andpressure changes can be variable and/or adjustable, for example.

In various instances, the supplemental, pulse-inducing pump or pumps ofa hydraulic fracturing system can be in signal communication with acontroller. For example, referring again to FIG. 5, a controller 550 cantransmit signals to the pumps 540 a, 540 b along the communication lines552 a, 552 b, respectively. Additionally, an operator can input commandsto the controller 550 to affect a pulse and/or sequence of pulses. Thecommands to the controller 550 can depend on the hydraulic fracturingsite and/or conditions. In various instances, the controller 550 cancommand the supplemental pump or pumps 540 a, 540 b to generate periodicpulses of a specific amplitude and at a specific frequency. In otherinstances, the controller can command the supplemental pump or pumps 540a, 540 b to generate an intermittent pulse of a specific amplitude at aspecific time, for example. In instances where multiple, pulse-inducingsupplemental pumps are incorporated into a hydraulic fracturing system,each supplemental pump can be independently controlled to differentamplitudes, frequencies, and/or times, for example. In other instances,multiple supplemental pumps can be coordinated and/or synchronouslycontrolled.

Referring now to FIG. 10, a hydraulic fracturing method is disclosed. Atstep 1010, the method can include generation of a fluid stream from aprimary pumping system. For example, the primary pumping system caninclude a plurality of primary pumps, such as the pumps 110 (FIGS. 1-5),for example, which can pump fluid into a manifold. Thereafter, at step1012, a first portion of the fluid stream can be directed along aprimary path. For example, the first portion of the fluid stream can bedirected toward a primary outlet of the manifold. Additionally, a secondportion of the fluid stream can be directed along a supplemental path.For example, the second portion of the fluid stream can be directedtoward a second outlet, which can be in fluid communication with asupplemental pump, such as supplemental pump 240, 540 a, and/or 540 b,for example. In certain instances, step 1012 and 1014 can occursimultaneously. In some instances, step 1014 can occur before step 1012or vice versa, for example. In various instances, the second portion ofthe fluid stream can be diverted to the supplemental outlet beforeproppants and/or other additives are pumped into the fluid stream.

Referring still to FIG. 10, at step 1016 a pulsed output can begenerated from the second portion of the fluid stream. For example, asupplemental pumping system can include at least one pulse-inducingpump, which can receive the second portion of the fluid stream via thesupplemental outlet and can pump the second portion of the fluid streamto generate a pulse of fluid. In such instances, the pulse or pulsesgenerated at step 1016 can be mechanically induced pulses, which aregenerated outside of the wellbore. In other words, the pulses of fluidare generated upstream of a wellhead, such as the wellhead 116 (FIGS.1-5), for example.

At step 1020, the pulsed output from the supplemental pump system can bedirected into the first portion of the fluid stream. For example, thepulsed output can be pumped into the first portion of the fluid streamat the manifold, at the wellhead, and/or between the manifold and thewellhead. As a result, the combined fluid stream can enter the wellheadand be forced down the wellbore and into the formation.

Throughout the steps 1010, 1012, 1014, 1016 and 1020 described above, amonitoring unit can monitor the fluid stream from the primary pumpingsystem and the supplemental pumping system. Moreover, a controller cancontrol the primary and/or supplemental pumps throughout the steps 1010,1012, 1014, 1016 and 1020. For example, the pulsing sequences, includingfrequency and/or amplitude, for example, can be adjusted throughout theprocess.

In various instances, a pulse-inducing system can be employed togenerate pulses in a hydraulic fracturing system. The pulse-inducingsystem can generate pulses of fracturing fluid, and can transfer thepulses of fracturing fluid into the fluid stream generated by theprimary pumps. The pulse-inducing system can include a pressure storagevessel and a pulsation valve, which can release a pulse or wave offracturing fluid. The pulse of fluid can be transferred into the fluidstream and subsequently fed down the wellbore. In certain instances, thepulse-inducing system can provide periodic pulses, for example, whichcan generate corresponding periodic pressure increases or spikes withinthe fluid stream. For example, the pulse-inducing system can deliver apulsed output, such as the pulsed output 640 (FIGS. 6-9), pulsed output740 (FIG. 7), pulsed output 840 (FIG. 8), and/or pulsed output 940 (FIG.9), for example. In other instances, the pulses can be intermittentand/or sporadic. An operator can control the pulse-inducing system todeliver pulses periodically and/or sporadically, for example.

In certain instances, multiple subsystems and/or pulsation valves can beconfigured to generate pulses of fracturing fluid, which can bedelivered to the fluid stream. The pulses can be output from differentpulsation valves and can have different frequencies and/or differentamplitudes, for example. In various instances, the pulses from differentsubsystems and/or pulsation valves can overlap, and/or can concurrentlyjoin the fluid stream. In other instances, the pulses can be staggeredand/or can intermittently join the fluid stream. In certain instances,at least one pulsation valve can be configured to deliver small pulsesto the fluid stream, and at least one pulsation valve can be configuredto deliver larger pulses to the fluid stream (see, e.g., FIGS. 7-9). Forexample, the pulse-inducing system can include multiple pressure storagevessels, which can maintain different pressure levels, and eachpulsation valve can be coupled to a different pressure storage vessel torelease pulses of different magnitudes.

Larger pulses of fracturing fluid can break apart rock formations, thusproviding more channels and/or fissures within the formation.Additionally, larger pulses of fracturing fluid can stimulate proppantsand lubricants in the fracturing fluid, and can force additionalproppants and lubricants within the fissures. Larger pulses offracturing fluid can also increase abrasion within the fissures, whichcan further enlarge a fissure. Moreover, larger pulses of fracturingfluid can provide a shock signal to the operator of the hydraulicfracturing system.

Smaller pulses of fracturing fluid can also stimulate proppants in thefracturing fluid, which can force additional proppants within thefissures. As proppants are forced further into the fissures, thefissures can be enlarged. Additionally, the smaller pulses of fracturingfluid can also provide a shock signal to the operator of the hydraulicfracturing system.

Referring now to FIG. 11, a hydraulic fracturing system 1200 isdepicted. Similar to the system 200, the hydraulic fracturing system1200 includes the primary pumps 110, the motors 114, the vehicles 112,the fluid lines 120 extending from the primary pumps 110, and thewellhead 116 of the wellbore. The hydraulic fracturing system 1200 alsoincludes the manifold 218, which includes the plurality of inlets 230fluidically coupled to the fluid lines 120. Accordingly, the fluid lines120 permit fluid communication between the pumps 110 and the manifold218. As depicted in FIG. 11, the manifold 218 also includes the primaryoutlet 232, which is coupled to the primary conduit 1222. The primaryconduit 1222 extends between the manifold 218 and the wellhead 116, andcan operably permit a fluid stream to flow from the manifold 218 to thewellhead 116. Similar to the hydraulic fracturing system 200, theprimary pumps 110 can supply a constant flow rate and a uniform pressureinto the manifold 218. As a result, the flow rate and pressure of thefracturing fluid exiting the manifold 218 can be constant orsubstantially constant.

Referring still to FIG. 11, the hydraulic fracturing system 1200includes a pulse-inducing system 1240, which is described in greaterdetail herein. The pulse-inducing system 1240 can be in fluidcommunication with the manifold 218 via the supplemental outlet 234 tothe manifold 218 and the supplemental conduit 238. For example, a firstportion of the fluid stream that is injected or pumped into the manifold218 from the primary pumps 110 via the fluid lines 120 can flow from theinlets 230 toward the primary outlet 232. Additionally, a second portionof the fluid stream that is injected or pumped into the manifold 218from the primary pumps 110 can be diverted to the supplemental outlet234. The second portion of the fluid stream can flow to thepulse-inducing system 1240, for example. In other instances, thepulse-inducing system 1240 can comprise a separate and/or independentfluid supply, and the entire fluid stream injected into the manifold 218can be directed to the primary outlet 232 and primary conduit 1222.

In various instances, the pulse-inducing system 1240 can be configuredto induce at least one pulse of fluid into the fluid stream outside ofthe wellbore. For example, the pulse-inducing system 1240 can generate apulse of fracturing fluid, which can flow from the system 1240 throughone of the connecting conduits 1241, 1242. Thereafter, the pulse offluid can join the fluid stream generated by the primary pumps 110.

Referring still to the embodiment depicted in FIG. 11, the connectingconduits 1241, 1242 can extend between the pulse-inducing system 1240and the primary conduit 1222 of the hydraulic fracturing system. Asdescribed in greater detail herein, each connecting conduit 1241, 1242can be coupled to a separate sub-system of the pulse-inducing system1240. For example, the first conduit 1241 can transfer a first pulse orfirst plurality of pulses from a first sub-system of the pulse-inducingsystem 1240, and the second conduit 1242 can transfer a second pulse orsecond plurality of pulses from the second sub-system of thepulse-inducing system 1240. In other instances, a single conduit canextend between the pulse-inducing system 1240 and the primary conduit1222. Alternatively, more than two conduits can extend between thepulse-inducing system 1240 and the primary conduit 1222. For example, ifa pulse-inducing system includes three (3) subsystems and three (3)corresponding pulsation valves, three (3) connecting conduits can extendbetween the pulse-inducing system and the hydraulic fracturing system.

The pulse or pulses generated by the pulse-inducing system 1240 can begenerated outside of the wellbore, for example, and can be transmittedto the fluid stream outside of the wellbore, for example. In variousinstances, the pulse or pulses can enter the fluid stream downstream ofthe plurality of inlets 230 to the manifold 218. For example, the pulsescan be introduced to the fluid stream between the manifold 218 and thewellhead 116. In various instances, the pulse-inducing system 1240 cantransmit the pulses to the connecting conduits 1241, 1242, and theconnecting conduits 1241, 1242 can be coupled to the primary conduit1222. For example, as depicted in FIG. 11, the connecting conduits 1241,1242 and the primary conduit 1222 can be coupled at an auxiliarymanifold 1236 or union intermediate the manifold 218 and the wellhead116.

In other instances, the pulse-inducing system 1240 can transmit thepulse or pulses to the fluid stream at the wellhead 116. For example,referring to FIG. 12, a hydraulic fracturing system 1300 is depicted.The hydraulic fracturing system 1300 can be similar to the hydraulicfracturing system 1200, except the connecting conduits 1241, 1242 canextend between the pulse-inducing system 1240 and the wellhead 116. Insuch instances, the pulse(s) from the pulse-inducing system 1240 can betransmitted to the stream of fracturing fluid at the wellhead 116.

In still other instances, the pulse-generating system 1240 can transmitthe pulse or pulses to the fluid stream within the primary manifold. Forexample, referring to FIG. 13, a hydraulic fracturing system 1400 isdepicted. The hydraulic fracturing system 1400 can be similar to thehydraulic fracturing system 1200. Additionally, the hydraulic fracturingsystem 1400 can include a primary manifold 1418 having a plurality ofinlets 1430 in fluid communication with the primary pumps 110 via thefluid lines 120. The manifold 1418 can also include a primary outlet1432 in fluid communication with the wellhead 116 and a supplementaloutlet 1434 in fluid communication with the pulse-inducing system 1240via supplemental conduit 1438. The manifold 1418 depicted in FIG. 13further includes a plurality of supplemental inlets 1435, 1436downstream of the primary inlets 1430. In the depicted arrangement, theconnecting conduits 1241, 1242 extend between the pulse-inducing system1240 and the supplemental inlets 1435, 1436, respectively, such that thepulse or pulses generated by the pulse-inducing system 1240 are directedinto the fluid stream at the manifold 1418.

In various arrangements described herein, the pulse-inducing system 1240(FIGS. 11-13) can receive fluid input from the manifold 218 (FIGS. 11and 12) or the manifold 1418 (FIG. 13), for example. In other words, aportion of the fluid stream pumped into the manifold 218, 418 can bediverted to the pulse-inducing system 1240. In such arrangements, thepulse-inducing system 1240 can receive a portion of the fluid pumpedinto the system 1200, 1300, 1400 from the primary pumps 110. In variousinstances, the portion of the fluid stream directed to thepulse-inducing system 1240 can be diverted from the fluid stream beforeproppants and/or other additives are added to the fluid stream.Accordingly, clogging and/or contamination of the pulse-inducing system1240 and/or various sub-systems and/or components thereof by proppants,for example, can be prevented and/or minimized.

In certain instances 5%-50% of the fluid from the primary pumps 110 canbe diverted to the pulse-inducing system 1240. For example,approximately 25% of the fluid from the primary pumps 110 can bediverted to the pulse-inducing system 1240. In other words, as anexample, if 80 barrel units were pumped into the manifold 218 (FIGS. 2and 3) of the manifold 418 (FIG. 4), for example, 60 barrel units couldbe directed to the primary outlet 1432 (FIG. 4) as a fluid stream, and20 barrel units could be directed to the supplemental outlet 1434 (FIG.4). In other instances, less than 5% or more than 50% of the fluid fromthe primary pumps 110 can be diverted to the pulse-inducing system 1240.

In various arrangements, the primary pumps 110 can generate a maximumpressure in the manifold 218 (FIGS. 11 and 12) or manifold 1418 (FIG.13), for example. For example, when each primary pump 110 is operated toits maximum capacity, a maximum operating pressure P_(max) can beachieved in the manifold 218, 418. Moreover, when a portion of the fluidstream is diverted to the pulse-inducing system 1240, as describedherein, the pressure in the manifold 218, 418 may drop. In certaininstances, the pressure can drop 5%-50% in the manifold 218, 418. Forexample, the pressure can drop approximately 25% within the manifold218, 418. In other instances, the pressure drop can be less than 5% ormore than 50%. When the pulse-inducing system 1240 redirects thediverted fluid stream back into the primary fluid stream as a pulse orwave of fluid, the pressure can increase toward the maximum pressureP_(max), for example. In certain instances, the pressure in the fluidstream can approach P_(max), however, the pressure may not reach P_(max)due to frictional losses, for example. For example, the total pressurefrom the fluid stream in combination with the peak of each pulse canapproach P_(max) of the system.

A pulse-inducing system can include at least one pressure storagevessel, which can store a volume of fluid at a pressure. When thepressurized fluid is released from the pressure storage vessel, a pulseof fluid can flow from the pressure storage vessel. As described herein,the pulse of fluid can be directed into a fluid stream of a hydraulicfracturing system outside of the wellbore. The pulse-inducing system caninclude at least one supplemental pump, which can supply fluid to thepressure storage vessel. The fluid can include water and/or chemicals,and can comprise a fracturing fluid, for example. The pulse-inducingsystem can also include at least one pulsation valve, which can befluidically coupled to one of the pressure storage vessels. Thepulsation valve can control the release of fluid from the pressurestorage vessel. For example, the amount of time the pulsation valve isopen, the degree of opening of the pulsation valve, and the frequency ofthe pulsation valve opening, can affect the duration, magnitude, andfrequency of the pulse or pulses, respectively.

In various instances, a pulse-inducing system can include multiplesubsystems. In each subsystem, different pressures can be maintained.For example, each subsystem can include at least one pressure storagevessel, which can be sealed from the other subsystem(s). Each subsystemcan further include at least one pump to supply fluid to the pressurestorage vessel and at least one pulsation valve to release fluid fromthe pressure storage vessel. As described in greater detail herein, thesubsystems can be operably connected to form one system at one pressure,for example, and can be operably disconnected to maintain differentpressures.

Referring now to FIG. 14, a pulse-inducing system 1240 is depicted. Inthe depicted embodiment, the supplemental conduit 238 provides a fluidinlet to the pulse-inducing system 1240 and the connecting conduits1241, 1242 provide a fluid outlet from the pulse-inducing system 1240.In various instances, the supplemental conduit 238 can deliver fluidfrom the primary manifold 218 or manifold 1418, for example, to thepulse-inducing system 1240. In other instances, the pulse-inducingsystem 1240 can include an independent fluid source. For example, adesignated supply vehicle, well and/or another suitable fluid supply canprovide fluid to the pulse-inducing system 1240.

The pulse-inducing system 1240 depicted in FIG. 14 further includes aninput manifold 1249 from which a plurality of input conduits 1243 a,1243 b, 1243 c, 1243 d extend. The input conduits 1243 a, 1243 b,1243 c,1243 d provide fluid pathways from the input manifold 1249 to thesupplemental pumps 1246 a, 1246 b, 1246 c, 1246 d. In the depictedarrangement, the pulse-inducing system 1240 includes four input conduits1243 a, 1243 b, 1243 c, 1243 d, which deliver fluid from thesupplemental conduit 238 and the input manifold 1249 to foursupplemental pumps 1246 a, 1246 b, 1246 c, 1246 d. For example, thefirst input conduit 1243 a can supply fluid to the first supplementalpump 1246 a, the second input conduit 1243 b can supply fluid to thesecond supplemental pump 1246 b, the third input conduit 1243 c cansupply fluid to the third supplemental pump 1246 c, and/or the fourthinput conduit 1243 d can supply fluid to the fourth supplemental pump1246 d.

As discussed above, the pulse-inducing system 1240 can include aplurality of supplemental pumps 1246 a, 1246 b, 1246 c, 1246 d. In otherinstances, the pulse-inducing system 1240 can include a singlesupplemental pump, as described in greater detail herein. In theembodiment depicted in FIG. 14, a power unit 1244 a, 1244 b, 1244 c,1244 d is coupled to each supplemental pump 1246 a, 1246 b, 1246 c, 1246d. For example, each power unit 1244 a, 1244 b, 1244 c, 1244 d cancomprise a motor, which can provide power and drive each supplementalpump 1246 a, 1246 b, 1246 c, 1246 d. As described in greater detailherein, the supplemental pumps 1246 a, 1246 b, 1246 c, 1246 d cangenerate and/or maintain pressure in the pulse-inducing system 1240.

In other instances, the pulse-inducing system 1240 can include fewerinput conduits and fewer supplemental pumps. For example, thepulse-inducing system 1240 can include a single input conduit and asingle supplemental pump, as described in greater detail herein.Alternatively, the pulse-inducing system 1240 can include a two or threeinput conduits and two or three supplemental pumps. In still otherinstances, the pulse-inducing system 1240 can include more than fourinput conduits and more than four supplemental pumps. In variousinstances, the number of input conduits can correspond to the number ofsupplemental pumps such that an input conduit provides a fluid pathwayto each supplemental pump. In still other instances, multiple conduitscan supply fluid to each supplemental pump, for example.

In various instances, the supplemental pumps 1246 a, 1246 b, 1246 c,1246 d can be configured to pump fluid into a first system manifold 1252via output conduits 1248 a, 1248 b, 1248 c, 1248 d. For example, thefirst system manifold 1252 can include a plurality of inlets or fittings1290, which can be coupled to and/or receive an end of each outputconduits 1248 a, 1248 b, 1248 c, 1248 d. In such instances, the outputconduits 1248 a, 1248 b, 1248 c, 1248 d and fittings 1290 can provide afluid pathway from each supplemental pump 1246 a, 1246 b, 1246 c, 1246 dto the first system manifold 1252.

The first system manifold 1252 depicted in FIG. 14 includes a first side1254 and a second side 1256. A first group of inlets 1290 are positionedin the first side 1254 and a second group of inlets 1290 are positionedin the second side 1256. In the depicted embodiment, an isolation valve1286 is positioned between the first side 1254 and the second side 1256.In such instances, the isolation valve 1286 can operably seal the firstside 1254 from the second side 1256. For example, when the isolationvalve 1286 is closed, the fluid pathway between the first side 1254 andthe second side 1256 can be closed such that fluid entering the inlets1290 in the first side 1254 is isolated and kept separate from fluidentering the inlets 1290 on the second side 1256. Moreover, when theisolation valve 1286 is open, the fluid pathway between the first side1254 and the second side 1256 can be open such that fluid entering theinlets 1290 in the first side 1254 can mix with the fluid entering theinlets 1290 on the second side 1256. As described in greater detailherein, the isolation valve 1286 can work in conjunction with anisolation valve 1288 to seal the subsystems of the pulse-inducing system1240.

In various instances, as depicted in FIG. 14, the first system manifold1252 can include additional inlets or fittings 1290. When additionalsupplemental pumps and corresponding output conduits are added to thepulse-inducing system 1240, the additional fittings 1290 can beconfigured to receive the additional output conduits. Additionally,various fittings 1290 can be sealed if one or more of the outputconduits are disconnected from the first system manifold 1252.

At least one supply conduit 1268 a, 1268 b can extend from the firstsystem manifold 1252 to one of the pressure storage vessels 1270 a, 1270b. Referring to the embodiment depicted in FIG. 14, a first supplyconduit 1268 a can extend from the first side 1254 of the first systemmanifold 1252 and a second supply conduit 1268 can extend from thesecond side 1256 of the first system manifold 1252. When the isolationvalve 1286 is closed, the fluid pathway between the first side 1254 andthe second side 1256 can be closed such that only fluid entering theinlets 1290 in the first side 1254 is channeled to the first supplyconduit 1268 a and only fluid entering the inlets 1290 in the secondside 1256 is channeled to the second supply conduit 1268 b. Moreover,when the isolation valve 1286 is open, the fluid pathway between thefirst side 1254 and the second side 1256 can be open such that fluidentering the inlets 1290 in the first side 1254 and the second side 1256may be transferred to both of the supply conduits 1268 a, 1268 b. Asdescribed in greater detail herein, the isolation valve 1286 can work inconjunction with an isolation valve 1288 to seal the subsystems of thepulse-inducing system 1240.

Referring still to FIG. 14, the first supply conduit 1268 a can extendfrom the first system manifold 1252 to the first pressure storage vessel1270 a, and the second supply conduit 1268 b can extend from the firstsystem manifold 1252 to the second pressure storage vessel 1270 b. Thesupplemental pumps 1246 a, 1246 b, 1246 c, 1246 d can pump fluid intothe pressure storage vessels 1270 a, 1270 b via the first systemmanifold 1252 to build and/or maintain pressure in the storage vessels1270 a, 1270 b. In various instances, the pressure storage vessels 1270a, 1270 b can include a pressure valve 1272, which can be employed toincrease the pressure in the system. For example, a gas such as ambientair, for example, can be pumped into the pressure storage vessel via thepressure valve 1272 to further increase the pressure therein. In otherinstances, the pressure valve can release and/or neutralize the pressurein the vessel 1270 a, 1270 b.

The pressure storage vessels or tanks 1270 a, 1270 b can be 100 gallonvessels, 200 gallon vessels, 300 gallon vessels, or larger, for example.A larger tank can provide more even pressures during pulsing. If thepressure in a pressure storage tank is 0 psi, no pulse of fluid can bereleased. However, if the pressure in the pressure storage tank isincreased, such as to 4,000 psi, for example, a small pulse of fluid canbe released. As the pressure in a pressure storage vessel is furtherincreased, such as to 10,000 psi, 15,000 psi, or 20,000 psi, forexample, successively larger pulses of fluid can be available. Invarious instances, the pressure in a pressure storage vessel can beincreased up to the maximum pump pressure to obtain the largest pulses,for example.

In various instances, one or more supplemental pumps can provide fluidto each of the pressure storage vessels. When the isolation valve 1286is closed (along with the isolation valve 1288 described in greaterdetail herein), the supplemental pumps 1246 a, 1246 b coupled to thefirst side 1254 of the first system manifold 1252 can be configured tobuild and/or maintain pressure in the first pressure storage vessel 1270a, and the supplemental pumps 1246 c, 1246 d coupled to the second side1256 of the first system manifold 1252 can be configured to build and/ormaintain pressure in the second pressure storage vessel 1270 b. In suchinstances, the first pressure storage vessel 1270 a and the secondpressure storage vessel 1270 b can obtain different pressures. Forexample, the first pressure storage vessel 1270 a can obtain a pressureof 6000 psi, and the second pressure storage vessel 1270 b can obtain apressure of 4000 psi or vice versa, for example. In other instances, thefirst pressure storage vessel 1270 a can obtain a pressure of 8000 psi,for example, and the second pressure storage vessel 1270 b can obtain apressure of 4000 psi or vice versa, for example. In other instances,even when the first and second subsystems 1250 a, 1250 b are isolatedfrom each other, the pressure storage vessels 1270 a, 1270 b can be setto maintain the same or substantially the same pressure.

When the isolation valve 1286 is open, the supplemental pumps 1246 a,1246 b, 1246 c, 1246 d coupled to both sides 1254, 1256 of the firstsystem manifold 1252 can be configured to build and/or maintain pressurein both pressure storage vessels 1270 a, 1270 b. In such instances, thefirst pressure storage vessel 1270 a and the second pressure storagevessel 1270 b can obtain the same or substantially the same pressure.

As depicted in FIG. 14, the pressure storage vessels 1270 a, 1270 b cansupply fluid to a second system manifold 1258 via inlet conduits 1266 a,1266 b. Moreover, the second system manifold 1258 can include outlets orfittings 1264 a, 1264 b which can fluidically couple the second systemmanifold 1258 to the pulsation valves 1280 a, 1280 b. The pulsationvalves 1280 a, 1280 b are configured to deliver pulses of fluid to theconnecting conduits 1241, 1242, respectively. For example, the pulsationvalves can be opened to varying degrees or percentages. In suchinstances, the degree to which the pulsation valve is opened can affectthe volume of fluid released from the pressure storage vessel 1270 a,1270 b per unit time. The second system manifold 1258 depicted in FIG.14 includes a first side 1260 and a second side 1262. The first outlet1264 a is positioned in the first side 1260 and the second outlet 1264 bis positioned in the second side 1262.

In various instances, an isolation valve 1288 can be positioned betweenthe first side 1260 of the second system manifold 1258 and the secondside 1262 of the second system manifold 1258. In such instances, theisolation valve 1288 can operably seal the first side 1260 from thesecond side 1262. For example, when the isolation valve 1288 is closed,the fluid pathway between the first side 1260 and the second side 1262can be closed such that fluid entering the second system manifold 1258via the first inlet conduit 1266 a is isolated and kept separate fromfluid entering the second system manifold 1258 via the second inletconduit 1266 b. In such instances, only fluid from the first pressuresupply vessel 1270 a can be supplied to the first pulsation valve 1280a, and only fluid from the second pressure supply vessel can be suppliedto the second pulsation valve 1280 b. Moreover, when the isolation valve1288 is open, the fluid pathway between the first side 1260 and thesecond side 1262 can be open such that fluid entering the manifold 1258from the first inlet conduit 1266 a can mix with the fluid entering themanifold 1258 from the second inlet conduit 1266 b.

In various instances, the first pulsation valve 1280 a can release avolume of pressurized fluid, and the second pulsation valve 1280 b canalso release a volume of pressurized fluid. When the isolation valves1286, 1288 are closed, the pulse-inducing system 1240 depicted in FIG.14 can comprise a pair of subsystems 1250 a, 1250 b. In such instances,the first subsystem 1250 a can comprise the first and second power units1244 a, 1244 b, the first and second supplemental pumps 1246 a, 1246 b,the first side 1254 of the first system manifold 1252, the firstpressure storage vessel 1270 a, the first side 1260 of the second systemmanifold 1258, and/or the first pulsation valve 1280 a, for example.Moreover, the second subsystem 1250 b can comprise the third and fourthpower units 1244 c, 1244 d, the third and fourth supplemental pumps 1246c, 1246 d, the second side 1256 of the first system manifold 1252, thesecond pressure storage vessel 1270 a, the second side 1262 of thesecond system manifold 1258, and/or the second pulsation valve 1280 b,for example.

In such instances, the first subsystem 1250 a can be configured todeliver pressure pulses of a first magnitude, first frequency, and firstduration to the hydraulic fracturing system, and the second subsystem1250 b can be configured to deliver pressure pulses of a secondmagnitude, second frequency, and second duration to the hydraulicfracturing system. In various instances, the first magnitude can bedifferent than the second magnitude, the first frequency can bedifferent than the second frequency, and/or the first duration can bedifferent than the second duration (see, e.g. FIGS. 7-9).

In instances where the isolation valves 1286, 1288 are open, thepressure in the first pressure storage vessel 1270 a can be equal to orsubstantially equal to the pressure in the second pressure storagevessel 1270 b. Accordingly, the magnitude of pulses from the firstpulsation valve 1280 a can be equal to or substantially equal to themagnitude of pulses from the second pulsation valve 1280 b. However, invarious instances, the first pulsation valve 1280 a can be configuredand/or controlled to deliver pulses of a first frequency and firstduration to the hydraulic fracturing system, and the second pulsationvalve 1280 b can be configured and/or controlled to deliver pressurepulses of a second frequency and second duration to the hydraulicfracturing system. In various instances, the first frequency can bedifferent than the second frequency, and/or the first duration can bedifferent than the second duration. Moreover, the first pulsation valve1280 a can be opened a first degree and the second pulsation valve 1280b can be opened a second degree. The degree of valve opening can affectthe volume of fluid released from the pressure storage vessel 1270 a,1270 b.

In various instances, the supplemental pumps 1246 a, 1246 b, 1246 c,1246 d can be designed and/or rated to withstand a maximum pressurecapability. However, in certain instances, the operational pressure inthe pulse-inducing system 1240 and associated equipment can be designedand/or rated to exceed the maximum pressure capability of thesupplemental pumps 1246 a, 1246 b, 1246 c, 1246 d. In other words, thepulse-inducing system 1240 can generate pressure pulses that exceed thepressure output from the supplemental pumps 1246 a, 1246 b, 1246 c, 1246d.

In various instances, the various components of the pulse-inducingsystem 1240 can be in signal communication with a control system, suchas control system 1338 depicted in FIG. 14A. For example, a controller1350 can transmit signals to the supplemental pumps 1244 a, 1244 b, 1244c, 1244 d along the communication lines 1352 a, 1352 b, 1352 c, 1352 d,respectively. In certain instances, various supplemental pumps 1244 a,1244 b, 1244 c, 1244 d may be in communication with each other and/orshare a common communication line to the controller 1350, for example.

An operator can further affect the pulse-inducing system 1240 bycontrolling the isolation valves 1286, 1288. Referring to the embodimentdepicted in FIG. 14A, the controller 1350 can communicate with theisolation valves 1286, 1288 along communication paths 1354 a, 1354 b,respectively. For example, the operator can input commands to thecontroller 1350 to affect opening and/or closing of the isolationvalve(s) 1286, 1288, and thus, to determine the number of subsystems inoperation in the pulse-inducing systems. The number of sub-systems cancontrol the number of independent pulses and/or pulse patterns deliveredto the hydraulic fracturing system. In certain instances, the isolationvalves 1286, 1288 may be in communication with each other and/or share acommon communication line to the controller 1350 such that both valves1286, 1288 are either open or closed, for example.

Additionally, an operator can input commands to the controller 1350 toaffect a pulse and/or sequence of pulses. The commands to the controller1350 can depend on the hydraulic fracturing site and/or conditions. Invarious instances, the controller 1350 can be in signal communicationwith the pulsation valves 1280 a, 1280 b via communication lines 1356 a,1356 b, respectively. For example, the controller 1350 can control theopening and closing of the valves, and can set the degree or percentagethat a valve is opened. Accordingly, the controller 1350 can command thepulsation valves 1280 a, 1280 b to generate periodic pulses of specificamplitude(s) and at specific frequencies. In other instances, thecontroller can command the pulsation valves 1280 a, 1280 b to generatean intermittent pulse of a specific amplitude at a specific time, forexample. In instances where multiple pulsation valves 1280 a, 1280 b areincorporated into a hydraulic fracturing system, each of the pulsationvalves 1280 a, 1280 b can be independently controlled to differentamplitudes, frequencies, durations and/or times, for example. In otherinstances, multiple pulsation valves 1280 a, 1280 b can be coordinatedand/or synchronously controlled. For example, the pulsation valves 1280a, 1280 b may be in communication with each other and/or share a commoncommunication line to the controller 1350.

An alternative pulse-inducing system 1540 is depicted in FIG. 15. Thepulse-inducing system 1540 can be employed with various hydraulicfracturing systems disclosed herein, including hydraulic fracturingsystem 1200, 1300, and 1400, for example. Referring to FIG. 15, thepulse-inducing system 1540 includes a single power unit 1544 and asingle supplemental pump 1546 coupled to the power unit 1544. Thesupplemental conduit 238 can provide fluid to the supplemental pump1546. In the embodiment depicted in FIG. 15, the supplemental pump 1546can provide fluid to the pressure storage vessel 1570. The supplementalpump 1256 can pump fluid into the pressure storage vessels 1570 to buildand/or maintain pressure in the storage vessel 1570. In variousinstances, the pressure storage vessel 1570 can also include a pressurevalve 1572 similar to pressure valve 1272, for example.

In other instances, the pulse-inducing system 1540 can includeadditional power units and/or additional supplemental pumps. Forexample, one or more power units can provide power to each supplementalpump. Additionally or alternatively, a single power unit can powermultiple pumps. Moreover, the pulse-inducing system 1540 can includemultiple pumps, which are configured to generate pressure in a singlestorage vessel 1570. In certain instances, the pulse-inducing system1540 can include multiple pressure storage vessels, which can befluidically coupled to one or more supplemental pumps. In variousinstances, the pressure storage vessels may be fluidically coupledand/or otherwise balanced such that the pressure is evenly distributedbetween the pressure storage vessels.

Referring still the embodiment depicted in FIG. 15, the pulse-inducingsystem 1540 includes a pulsation valve 1580, which is configured todeliver pulses of fluid. The pulsation valve 1580 can be configuredand/or controlled deliver pulses having a first magnitude, firstduration, and/or first frequency, for example. As depicted in FIG. 15,the pulsation valve 1580 is fluidically coupled to an output conduit1542, which can deliver the pulse of fluid upstream of the wellhead 116.

In other instances, the pulse-inducing system 1540 can include more thanone pulsation valve 1580. In such instances, the pulsation valves can beconfigured to independently deliver pulses to the fluid stream. Forexample, the pulses can concurrently join the fluid stream and/or canalternatingly join the fluid stream, for example. When the pulses jointhe fluid stream in unison, the largest pulses can be achieved.

Referring now to FIG. 16, a hydraulic fracturing method is disclosed. Atstep 1602, the method can include generation of a fluid stream via aprimary pumping system. For example, the primary pumping system caninclude a plurality of primary pumps, such as the pumps 110, forexample, which can pump fluid into a primary manifold. Thereafter, atstep 1604, a pulsed output can be generated via a pulse-inducing system.For example, the pulse-inducing system 1240 and/or 1540 can generate apulse, multiple pulses, series of pulses, and/or multiples series ofpulses. The pulse or pulses generated at step 1604 can be generatedoutside of the wellbore. In other words, the pulses of fluid aregenerated upstream of a wellhead, such as the wellhead 116, for example.

At step 1606, the pulsed output from the pulse-inducing system can bedirected into the fluid stream. For example, the pulsed output can bepumped into the first portion of the fluid stream at the manifold, atthe wellhead, and/or between the manifold and the wellhead. As a result,the combined fluid stream can enter the wellhead and be forced down thewellbore and into the formation.

Throughout the steps 1602, 1604, 1606 described above, a monitoring unitcan monitor the fluid stream from the primary pumping system and/or thepulse-inducing system. Moreover, a controller, such as controller 1350,for example, can control the pulse-inducing system. For example, thepulsing sequences, including frequency, duration, and/or amplitude, forexample, can be adjusted throughout the process. In various instances,referring to FIG. 17, a controller can control at least one power unitof the pulse-inducing system at step 1702. For example, a controller canbe in signal communication with a power unit, such as power units 1244a, 1244 b, 1244 c, and 1244 d (FIG. 14) or the power unit 1544 (FIG. 15)to control the pressure in the system. Additionally or alternatively, acontroller can control the isolation valves of the pulse-inducing systemat step 1704. For example, a controller can be in signal communicationwith the isolation valves 1286 and 1288 (FIG. 14) to control the numberof subsystems in the system. Moreover, a controller can control at leastone pulsation valve of the pulse-inducing system at step 1706. Forexample, the controller can control and/or adjust the pulse and/orpulsing sequences, including frequency, duration, and/or amplitude. Invarious instances, steps 1702, 1704, and/or 1706 can occursimultaneously and/or iteratively. Moreover, the steps 1702, 1704,and/or 1706 can be implemented in various different sequences.

The reader will appreciate that the various hydraulic fracturing systemsand methods described herein can be employed in new wells and can beutilized at previously drilled wells to draw out additional oil and/orgas, for example. Additionally, the systems and methods described hereincan employ various pumps simultaneously and/or separately. In variousinstances, it may be advantageous to exclusively employ the supplementalpump(s) and/or pulse-inducing system described herein for at least aportion of a hydraulic fracturing operation. In such instances, theentire fluid stream from the primary pumps 110 can be diverted to asupplemental pump or pumps and/or pulse-inducing system.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

While the hydraulic fracturing systems and/or methods have beendescribed as having exemplary designs, the present invention may befurther modified within the spirit and scope of the disclosure. Thisapplication is therefore intended to cover any variations, uses, oradaptations of the invention using its general principles. Further, thisapplication is intended to cover such departures from the presentdisclosure as come within known or customary practice in the art towhich this invention pertains.

What is claimed is:
 1. A hydraulic fracturing system for introducingfracturing fluid into a wellbore, the system comprising: a pumpingsystem configured to generate a fluid stream; and a pulse-inducingsystem positioned downstream of the pumping system, wherein thepulse-inducing system comprises a supplemental pump.
 2. The hydraulicfracturing system of claim 1, wherein the pulse-inducing system furthercomprises a pressure storage vessel.
 3. The hydraulic fracturing systemof claim 2, wherein the pulse-inducing system further comprises apulsation valve.
 4. The hydraulic fracturing system of claim 3, whereinthe pressure storage vessel is positioned intermediate the supplementalpump and the pulsation valve.
 5. The hydraulic fracturing system ofclaim 1, wherein a portion of the fluid stream is diverted to thepulse-inducing system.
 6. A hydraulic fracturing system for introducingfracturing fluid into a wellbore, the system comprising: a manifold,comprising: a first fluid outlet; and a second fluid outlet, a pumpingsystem fluidically coupled to the manifold, wherein the pumping systemis configured to deliver a first fluid stream to the first fluid outletand a second fluid stream to the second fluid outlet; and apulse-inducing system positioned downstream of the second fluid outlet.7. The hydraulic fracturing system of claim 6, wherein thepulse-inducing system is configured to generate a pulsed output from thesecond fluid stream.
 8. The hydraulic fracturing system of claim 7,wherein the pulsed output is delivered upstream of the wellbore.
 9. Thehydraulic fracturing system of claim 6, wherein the pulse-inducingsystem comprises a pump.
 10. The hydraulic fracturing system of claim 9,wherein the pulse-inducing system further comprises a pressure storagevessel.
 11. The hydraulic fracturing system of claim 10, wherein thepulse-inducing system further comprises a pulsation valve.
 12. Thehydraulic fracturing system of claim 11, wherein the pressure storagevessel is positioned intermediate the pump and the pulsation valve. 13.The hydraulic fracturing system of claim 6, wherein the manifold furthercomprises a plurality of inlets, wherein the pumping system furthercomprises a plurality of pumps, and wherein each of the pumps isfluidically coupled to one of the inlets.
 14. A hydraulic fracturingsystem for introducing fracturing fluid into a wellbore, the systemcomprising: a pumping system configured to generate a fluid stream whichis directed toward the wellbore; and a pulse-inducing system, wherein aportion of the fluid stream is diverted through the pulse-inducingsystem, wherein the pulse-inducing system is configured to generate apulsed output, and wherein the pulsed output is delivered to the fluidstream upstream of the wellbore.
 15. The hydraulic fracturing system ofclaim 14, wherein the pulse-inducing system comprises a pump.
 16. Thehydraulic fracturing system of claim 15, wherein the pulse-inducingsystem further comprises a pressure storage vessel.
 17. The hydraulicfracturing system of claim 16, wherein the pulse-inducing system furthercomprises a pulsation valve.
 18. The hydraulic fracturing system ofclaim 17, wherein the pressure storage vessel is positioned intermediatethe pump and the pulsation valve.
 19. A method for introducingfracturing fluid into a wellbore, wherein the method comprises:generating a fluid stream via a primary pumping system; diverting aportion of the fluid stream to a pulse-inducing system; generating apulsed output via the pulse-inducing system; and directing the pulsedoutput into the fluid stream upstream of the wellbore.
 20. The method ofclaim 19, wherein generating the pulsed output comprises at least one ofcontrolling a pump of the pulse-inducing system.